This invention relates generally to footwear and, more particularly, to an improved method of selectively strengthening the upper, midsole, insole, and outsole components of footwear.
Conventional shoe construction involves a number of molding steps. Those molding steps that involve the midsole and outsole components are typically quite expensive. Some molding can be done economically on the toe, heel, and lace pieces of the upper. Compression and injection molding techniques are most commonly employed in the athletic shoe industry.
Prior art attempts at strengthening the materials used in molding shoes have included additives for reducing slip resistance and increasing the durability of certain wear areas of outsoles. In addition, pieces of plastic or other material are sometimes glued to the midsole to strengthen compression areas and thereby protect against excessive pronation and to provide a foot bridge for the midfoot area.
It would be advantageous to provide an improved method for constructing shoes that minimizes the molding steps required to thereby reduce the cost of production. It would also be advantageous to provide an improved method for constructing shoes that selectively strengthens midsole, upper, and outsole components, and that increases the durability or resistance to wear of selected areas of those components.
In accordance with the illustrated preferred embodiments of the present invention, a sprayed material forms the entire outsole or is simply applied over one or more selected areas of a conventional molded outsole to increase the durability of those areas of the outsole. In addition, the sprayed material may be selectively applied to midsoles, uppers, and outsoles for purposes of reinforcement.
Cleated footwear used in soccer, football, and rugby traditionally have outsoles made from firm, high-density plastic, urethane or nylon materials. The present invention permits manufacturing such cleated footwear using lightweight foamed materials such as ethylene-vinyl acetate (EVA) foam or blown rubber, for example, to produce a midsole having a plurality of cleats formed on the bottom or outer surface thereof. In accordance with one aspect of the present invention, a coating of an elastic polymer, such as a urethane/rubber or polyurethane-containing material, is sprayed at an appropriate consistency and in appropriate thicknesses over the outer surface of the molded cleated midsole to form an outsole layer that provides desired durability, torsional stability, flexibility, and cushion characteristics. If cleated outsoles were to be constructed of soft foamed materials alone, they would be light weight and would exhibit superior shock absorption and flexibility characteristics, but would be seriously lacking in durability, stability, and traction. However, the addition of an elastomeric outer coating, selectively spray-applied, in accordance with the present invention, would overcome the negatives, while retaining the significant advantages of such construction.